In-vivo- und In-vitro-Untersuchungen zur myokardialen Kontraktilität vergleichend an Weißen-Neuseeland-Kaninchen und Chinchilla-Bastard-Kaninchen

Laboratory rabbits are frequently used in animal experimental research. The aim of the present study is to compare the heart functions of New Zealand White Rabbits (WN) to the one of Chinchilla Bastard Rabbits (CB) in vivo and in vitro. The higher stress susceptibility of New Zealand White Rabbits noticed in clinical observations is to be examined based on parameters of cardiac contractility. To determine the morphometric parameters and the contractile function of the heart, six animals at a time anaesthetized with Propofol are examined by means of echocardiography. As a result the thickness of the heart wall and the diameter of the left ventricle are determined, and the fractional shortening is calculated. All parameters are measured at the end of systole and diastole. In the next step single cardiomyocytes of six additional animals from each race are enzymaticly isolated from the removed hearts with a modified Langendorff-Perfusion-Apparatus. The contractility of the single cells is analysed under controlled conditions as well as under ß-agonist stimulation with Isoprenalin concentrations of 10-11 to 10-6 M. In terms of the strength of the heart wall or the left ventricle’s diameter, the ultrasound investigations don’t yield any significant differences. However Chinchilla Bastard Rabbits show a significantly higher fractional shortening (40,19 ± 3,19 %) than New Zealand White Rabbits (35,49 ± 3,78 %). Regarding the single cardiomyocytes a distinct difference in the duration of basal shortening can be noticed. WN clearly show a longer shortening period (255,80 ms) than CB (208,73 ms). Cardiomyocytes of WN respond to very low Isoprenalin concentrations from 10-11 to 10-10 M with a significantly higher shortening speed. Broad differences in the fractional shortening of the single cells arise during the experiments with the highest concentration of Isoprenalin (10-6 M). The fractional shortening of cardiomyocytes from WN amount to 7,47 %, whereas the cardiomyocytes from CB reach 9,89 %. On the single cell level WN react more sensitively to the stimulation with increasing Isoprenalin until a threshold of 10-8 M. Beyond that level the contractility decreases visible. However on the organ level the CB have basal a higher contractility. The breed specific results found in this research study could be caused by differences in sensitivity, regulation and the number of ß-receptors as well as by differences in anaesthetic behaviour. Further investigations on a biochemical and molecular level should be carried out to answer these questions.

Level thesis:degree_level

thesis.doctoral

Grantor dc:publisher

Ludwig-Maximilians-Universität

Year

2003

Author dc:creator

• Lück, Evelin

Repository record source_url

https://edoc.ub.uni-muenchen.de/1483/

OAI identifier oai:identifier

oai:edoc.ub.uni-muenchen.de:1483